1. Field of the Invention
The invention concerns devices for electrical connection of the type comprising a plug with multiple contacts designed to engage with the corresponding contacts of a socket.
2. Discussion of Background Information
It is known, notably through French Patent No. 1,448,070 and its patent of addition No. 90457, the disclosures of which are expressly incorporated by reference in their entireties, by the present assignee, for electrical connection devices to be produced in such a way that with a single model of socket and plug, always connected in the same plane of connection, it is impossible to combine two elements which can not be connected due to the nature of its currents corresponding to each of them. This means that with such a device, if a plug goes into a socket, the socket can supply it with the current that it uses, and conversely, if a plug will not go into a socket, the latter cannot supply the necessary current
As in the patent already mentioned, the invention relates mainly but not exclusively to the case of a socket with four contacts or poles spaced on a circumference and, possibly, a ground contact placed in the center.
Each of the two elements--plug and socket--is constituted by a housing and an insulating contact carrier mounted so as to be adjustable in relative orientation in relation to the housing while the housings of the two elements carry mating means for guiding and locking by rotation arranged so that these elements can only be joined together in a single relative angular position
The sockets with different power supplies (for example: 500 volts three-phase, 380 volts three-phase, 110 volts single-phase, 24 volts single-phase, etc.) and the corresponding plugs are differentiated by assigning each nominal current a given relative angular position of the contact carrier in its housing. When the number of these different relative positions is sufficient (of the order of twenty), i.e. at least equal to the number of industrial currents normally in use, it is possible to fix the position corresponding to a given current once and for all and thus establish a system of standardization valid for the industry as a whole.
In addition, a safety disk made of insulating material is mounted so as to pivot on the socket so as to be able to be entrained in rotation by the plug, coaxially with the circumference on which the contacts are located, when the plug is locked on the socket. This safety disk is provided with openings designed for passage of the contacts of the plug and spaced on a circumference lying over that on which the contacts are located and disposed such that at the end of the locking rotational movement only certain contact locations are uncovered, and means are provided so that this safety disk is locked in an initial position in which all the contacts are masked when the plug and the socket are disconnected.
In the known devices, the safety disk is locked in the selected initial position by engaging at least one protrusion carried out by a safety collar surrounding the contact carrier with one of a plurality of spaced slots on the periphery of the disk, the collar being drawn towards the disk by an elastic means and immobilized in rotation by guiding means. The collar is pushed back by the plug when the latter is introduced into the socket, allowing the safety disk to be unlocked. According to FR 2,212,655 in the name of the present assignee, and whose disclosure is expressly incorporated by reference thereto in its entirety, the slot corresponding to the correct initial position for the desired nominal current may advantageously only be unlocked at the time of initial assembly.
Such an embodiment has certain drawbacks which are due to the fact that the safety disk has a dual function to mask all the contact locations in the initial position and to uncover given contact locations in the final connection position.
This is why French Patent 2,270,696 in the name of the present assignee, and whose disclosure is expressly incorporated by reference thereto in its entirety, proposes to dissociate the two functions by means of a second so-called complementary disk made of insulating material which is mounted so as to pivot on the socket coaxially with the safety disk and arranged so as to be entrained in rotation at the same time as the latter between the initial position and the final connection position, the complementary disk being provided with openings equal in number to that of the contact locations on the socket and spaced in the same way as the latter, while the relative angular position of the socket and the complementary disk is such that the openings line up with the contact locations in the final position.
Thus, the complementary disk is designed to mask all the contact locations in the initial position while the safety disk retains its functions of selecting the contact locations to be uncovered in the final position.
In this known system the complementary disk has two diametrically opposite slots and the safety disk has a plurality of cavities spaced around its circumference.
The initial position of the two disks is assured by two protrusions projecting from a safety collar already mentioned previously in connection with the embodiment with a single disk, the protrusions being designed to engage both through the slots in the complementary disk and in two of the cavities in the safety disk.
It is understood that the initial position of the complementary disk is always the same, whereas that of the safety disk is selected at the same time of assembly according to the desired nominal current.
However, it is also clear that this position of the disks in relation to the socket is fixed and thus only corresponds to a single current, and is also only known to the initial assembler.
This is all the more of a nuisance as the installer generally tests the connections, for which he exerts pressure on the collar using any appropriate means, such as a plug in order to unlock the disks and turn them to uncover the contacts. Thus, in the course of the resetting operation, there is a risk of selecting another cavity for the safety disk and thus changing the relative position of the two disks.